Hand-held portable computers are used by a variety of enterprises including manufacturing firms, department, grocery and drug stores, transportation companies, package delivery services, insurance firms and utility companies. Hand-held computers are advantageously employed to facilitate such diverse business functions as inventory control, production scheduling and expediting, billing and both package route tracking.
Hand-held computers, including pen computers and touch screen computers, are gaining popularity in the band-held computer market. A pen computer is a portable computer including a housing enclosing a microprocessor and associated circuitry and an interactive visible display screen, often referred to as an electronic workslate. Instead of using a keyboard to enter data and initiate processing routines, a pen computer utilizes either a cordless electromagnetic pen or an electromagnetic pen tethered to the housing to interact with the microprocessor. By appropriately touching the display screen with the pen, a user may input data and access stored data, boot up an operating system, change screen displays or menus, select and run programs from a set of application and utility programs stored in computer memory and enter processing or query commands. The pen computer also includes a transceiver for transmitting and receiving data via radio frequency signals and input/output ports to interface with various devices.
A touch screen computer is similar to a pen computer but, instead of using an electromagnetic pen to interface with the computer, a touch sensitive display screen is provided and the user interfaces with the computer by appropriately touching areas of the display screen with his or her finger to execute commands, enter data, respond to prompts, etc.
As user mobility is a key advantage of hand-held computers, such computers will often be operated by a user who is standing or walking, e.g., a user entering inventory data into the computer while walking through a warehouse. To use a pen computer in a standing position, the electronic pen is grasped in the user's writing hand while the housing is supported in the other hand by grasping an edge of the housing with the hand such that the user's fingers extend over a bottom surface of the housing and a thumb extends over a portion of an upper surface of the computer housing. Alternately, the computer may be supported by the user's forearm. In this position, a lower surface of the computer rests on the forearm and palm and the user grips the computer by curling his or her fingers curl over an edge of the housing. Either method of holding the computer is awkward and tiring and requires an application of significant force by user to grip the computer. In addition, repetitive use of the computer can cause discomfort because the user must angle his or her wrist to orient the display screen in a readable position.
The weight of a pen computer is appreciable, approximately five pounds. Holding such a five pound instrument for extended periods with one hand will induce fatigue in the user's grasping hand, wrist and arm. Compounding this problem is the fact that the user must use the pen in his or her writing hand, thereby precluding the possibility of alternating the hand holding the computer to ameliorate fatigue.
Similarly, a touch screen computer is held in one hand or supported by the user's forearm as described above. The user employs the index finger of his or her free hand (usually the writing hand) to appropriately touch the screen. Ergonomic theories teach the importance of designing products suitable to human physiological capabilities and limitations. A pen computer or touch screen computer which does not provide an ergonomically proper means of holding and positioning the computer can lead to a marked decline in user productivity as the work day continues as a result of increasing fatigue. Additionally, subjecting a user of a pen or touch screen computer to hand, wrist and arm fatigue may result in long term health problems such as carpal tunnel syndrome.